1. Field
The teachings in accordance with the exemplary embodiments of this present disclosure generally relate to an inverter, and more particularly to a multilevel medium voltage inverter.
2. Background
In general, a multilevel medium voltage inverter is an inverter having an input power whose rms (root mean square) value is over 600V for a line-to-line voltage, and has several stages in output phase voltage. The multilevel medium voltage inverter is generally used to drive an industrial load of large inertia ranging from several kW to several MW capacities of, for a non-limiting example, fans, pumps, compressors, tractions, hoists and conveyors.
One form of multilevel inverter is a Cascaded H-Bridge (CHB) inverter architecture, which employs multiple series-connected H-Bridge inverters for driving each motor winding phase, or a cascaded NPC (Neutral Point Clamped) inverter transformed from the CHB inverter. The recently used NPC inverter is advantageous over the conventional cascaded CHB inverter due to smaller size. The multilevel inverter widely used in various fields requires a higher efficiency and a topology of smaller number of elements.